Power transmission



e 1944- F. T. HARRINGTON ETAL 2,351,263-

POWER TRANSMISSION Filed Dec. 30, 1939 2 Sheets-Sheet l INVENTORS FERRIST. HARRINGTON. RAYMOND c. GRIFFITH & R0 RT A. SHARTLE BY- z fm ATTORNEYI June 13, 1944.

F. T. HARRINGTON ETAL POWER TRANSMI SS ION 2 Sheets- Sheet 2 Filed Dec.30, 1939 INVENTORS Patented June 13, 1944 FICE rowmt TRANSMISSION FerrisT. Harrington and Raymond C. Griflith, Detroit, Mich, and Robert A.Shartle, Rockford, Ill., assignors to Vickers Incorporated, Detroit,

I Mich., a corporation of Michigan Application December 30, 1939, SerialN0. 311,856 I 1 Claim. (01. 1221-45) This invention relates to powertransmissions and more particularly to those of the type comprising twoor more fluid pressure energy translating devices, one of which mayfunction as a pump and another as a fluid motor.

The invention more particularly relates to power transmission controlsystems as used in various machine tools to drive the tool or workcarriages thereof. Control systems for machine tools providing theusually required rapid advance and two diflferent feed rates of thecarriage in one direction together with a rapid return movement havebecome standardized and are readily obtainable. Occasionally, however, aneed arises for other distinct cycles of operation and accordingly it isan object of the present invention to provide a power transmissionsystem utilizing a standard control system to produce a cycle 01operation including a rapid traverse stroke in each direction and a feedstroke in each directionof'traveh 7 Further objects and advantages ofthe present invention will be apparent from the following description,reference being had to the accompanying drawings wherein a preferredform of the present invention is clearly shown.

-Inthe drawings:

Figure 1 is a diagrammatic view of a fluid power transmission systemincorporating a preferred form of the present invention.

' Figure 2 is a simplified showing of Figure with the several valvesvarious positions.

In Figure 1 there is shown a pump I driven by a suitable prime moversuch as an electric motor I 2. The pmnp I0 has a suction conduit I4,through which fluid may be withdrawn from a tank 18, and a deliveryconduit I8. A relief valve 20 built on'the pump I0 is adapted to bypassthe delivery thereof whenever the pressure at the discharge side or thepump reaches a predetermined high point. p

A feed control panel generally designated at 22 has .formed therein abore 24 with annular ports 28, 28, 30, 32, 34 and 36 spaced along itslength as illustrated. For the purpose of controlling fluidcommunication between these variou ports a valve spool 38' having lands40, 42 and 44 is reciprocably mounted in bore 24. The port 30constitutes the pressure port and is connected by a passage 46 to the.pressure conduit I8 while the 1 therein shown in their piston 62 issubject to the pressure in'a chamber 12, which constitutes the outletofvalve 60,

through a restricted passage 14. A'passage 16 extends from chamber I2 tothe port 84 and has therein an adjustable throttle 18. Valve 38 andthrottle 18 are provided with drain passages 80 and 82 which connect totank passages 48 and 50 respectively. The panel 22 is a standard controlpanel usually utilized to provide a cycle of motor movements comprisingaforward stroke at both rapid traverse and feed rates and a retum strokeat rapid traverse rate only. In the present circuit the rapid traversereturn position or the plunger is not utilized, the operating means.hereafter described, being arranged to shift the control plunger 38 onlybetween itsstop, feed and rapid traverse forward positions. A. panel ofthe character described is disclosed in detail in the patent to Hermanet al. No. 2,274,603 issued Feb.-

Passages 54 and 58 connect to conduits 84 and 86 which form the pressureand tank lines respectively of a conventional solenoid-operated.four-way, reversing valve 88. A pair of conduits 90 and 92 connect thetwo cylinder ports of valve 88 to the right and left ends of a cylinder84 in which is slidably mounted a piston 80. A rod 88 of piston 88 issecured to and adapted to move a machine tool slide I00.

Three operating means are provided for shifting the valve spool 38,thefirstbeing a solenoid-actuated rod I02 mo*mted in a casing I04 whichis secured to the bottom of panel 22 and at right two end ports. 2 6 and38 constitute tank ports and are connected by passages 48. and 50-respectively to a tank conduit 52 extending it the tank I8.

Ports 28 and 32 have extending therefrom pas- I02 is limited to thatnecessary to shift the plunger 38 down only to the stop position,illustrated in Figure 1, that'is, while the-plunger 38 w might, in itsnormaluse, be shiftedbelowthe stop position to a rapid travers returnposition; the

rod I02 is arrangedto prevent such movement.

A hand lever H2 secured to one end of shaft ward travel.

6 provides the second means for shifting spool A cam II4, providing thethird means, is adjustably mounted on slide I80 and is adapted tocontact a roller I I6 on the upper end of spool 38 to shift the same aswill later be described. The cam; I I4 is preferably pivoted so as topass freely over the roller II6 when the table moves to the right and toactuate the roller only during left- For operation of the varioussolenoids an eleclower circuit of a push button starting switch II8connects one side of the line L by a conductor I20 and a branchconductor I22 to the lefthand solenoid I24, thence to the other side ofthe line L. The conductor I20 extends to a normally open limit switchI26, thence to line L Limit switch .trical circuit is provided. Thenormally open I26 is adapted to beoperated by a-cam I28 adjustablymounted on slide I80 when the latter is moving to the right only. Alimit switch I30 has its single circuit extend from line L by aconductor I32, the normally closed upper circuit of switch H8 and aconductor I34 to the righthand solenoid I36, thence to line I A branchlimit of its stroke. The normally open back circm't of switch I46extends from line L by a conductor I48 to the righthand solenoid I50 ofvalve 68. The normally open front circuit extends from line L through amanually operable see lector switch I58 ductor I 20. In Figure 2, thefluid flow through the several valves is shown in their diiferentrespective positions.

and by a conductor I60 to con- In operation, with the parts in thepositions shown in Figure 1 and the pump I0 operating and solenoids I36and I40 energized, fluid is with drawn from tank I6 through conduit I 8and delivered through conduit I8 and passage 46 to the pressure port 30in panel 22. As the land 40 of spool 38 is within port 28, fluid willpass from port 30 to port 26, through passage 46 and conduit 52 to tank.Thus, the machine is at rest with the pump delivery passing to tank.

To initiate a working cycle the push button starting switch H8 isdepressed to deenergize the solenoid I36 by breaking its circuitextending from switch I38 by conductors I32 and I34. At the same timethe lower circuit of switch H8 is closed to energize'solenoid I24through conductors I and I22. Accordingly solenoid I24 will shift rodI02 to the right causing rod I08 to rotate shaft I86 the arm III ofwhich will then shift spool 38 to its uppermost or rapid traverseposition (see Figure 2). Pressure fluid will then pass from port throughport 28, passage 54, conduit 84, valve 88 and conduit 86 to the rightend of cylinder 64. Piston 66 will move to the left with rod 88 movingslide I88 like- The limit switch I3. is adapted to be held startingswitch II8 may be released as the circuit for solenoid I36 then bebroken at switch I30. Slide I06 will move rapidly to the right until camII4 contacts roller II6 of spool 38 thereby causing the latter to beshifted downwardly to its feed position (Figure 2). In this positionpressure fluid will continue to be de-, livered to the right end ofcylinder 88 through the same path but port 32 will be' blocked by land42 thereby directing the exhaust fluid from passage 56 through passage58, hydrostatic valve -60, throttle I8, passage I6, ports 34 and 36.passage 50 and conduit 52 to tank. Accordingly, the exhaust fluid fromcylinder 84 is metered-therefrom by throttle I8 and hydrostatic valve 60to feed the slide I00 to the left. The pump delivery over what is neededby piston 86 is blown over the relief valve 20 to tank.

When slide I00 reaches the end of its leftward travel determined by thepositioning of cam I 44,

the latter will contact switch I46 and close it to energize solenoid I50,through conductor I48. Solenoid I50 will then shift valve 88 to reversethe fluid connections therein. As the same -flow connections exist inpanel 22, pressure fluid will be directed through conduit 84, valve 88and conduit 92 to the left end of cylinder 94 causing piston 96 andslide I00 to reverse and move to the right with cam I44 riding oil ofswitch I46. Exhaust fluid will pass from conduit 90, through valve 88and conduit 86 to panel 22 where it will 2 be metered, as previouslydescribed, to tank. The slide I00 accordingly feeds to the right untilcam- 7 switch [I8 and conductor I34 while solenoid I40 wise.- Exhaustfluid from cylinder 84 will pass will be energized through conductorsI32 and I38. Solenoid I36 will shift rod I02 to the left causing spool36 to be lowered to its stop positherethrough. Solenoid I40 will shiftvalve 88 to the position shown in Figure 1 in readiness for the nextcycle of operation which may be repeated by again depressing switch II8.

The above description applies where the device is used for only one feedrate in addition to the rapid traverse rate. The standard control panel22 provides in addition a second, slower, feed rate which is obtained bydepressing the plunger 38 to a position just below the feed positionillustrated in Figure 2. When theplunger 38 is thlls depressed all ofthe connections are the same 'as for coarse feed except that oilretm'ning'f' from the motor through hydrostatic valve 68, throttle I8and passage I6 cannot escape from port34 to tank port 36 but must flowthrough the finer throttle I52, passage I54 and port I56 in order toreach the tank port 36. Thus the feed rate is, under these conditions,determined by the much smaller opening at throttle I52.' It will beobvious to those skilled in the .art that suitable additional'cam's maybe provided for further depressing pllmger 38 to obtain a finer feed atany desired point in the table travel. Likewise by the use of hook camsthe plunger 38 may be lifted to coarse feed position or to rapidtraverse position at any point as may be found desirable for anyparticular work set up.

If it is desired to have a cycle of operation wherein the rightwardstroke starts at a rapid traverse rate and is later reduced to a feedrate,

I the selector switch I58 may be closed and the cam/(28 'moved to aposition such as that shown by dotted lines in Figure 1 where it willnot operate limit switch I26 but will, at an intermediate point in thestroke, depress the plunger 38 to feed position. Under these conditions,when the table reaches the lefthand limit of its stroke and cam Idepresses limit switch M8, the operation'is the same as before describedexcept that in-addition solenoid I24 is energized through the frontcircuit of switch 6, selector switch I58 and conductors I60, I20 andI22. Thus the plunger 38 is lifted to rapid traverse position at thestart of the rightward stroke and remains in this position untildepressed to feed position by the cam 28. The arrangement is thuscompletely flexible to provide any desired speed cycle in one directionof table travel and to provide an identical or different speed cycle inthe opposite direction.

If an emergency arises and it is desired to stop the slide I00 inwhatever position it maybe, the hand lever 2 may be rotated clockwise toshift spool 38 downwardly to its stop position. The

pump III will then be unloaded and the slide I 00 will stop.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claim whichfo1lows..-

What is claimed is as follows:

In a hydraulic power transmission system the combination with meansforming a source of pressure fluid, fluid motor means connected tothesource for operation thereby, a standard control panel connected betweenthe motor and source and of the type having a control member normallyshiftablebetween at least four positions providing rapid traverseforward, feed forward FERRIS r. HARRINGTON. RAYMOND c. GRIFFITH. ROBERTA. sum-rm.

